Geophysicist Merle Tuve proposed that an electronically-activated proximity fuse would make anti-aircraft fire far more effective, and led the team of scientists that developed the device, which proved crucial in the allies' victory in World War II. He was among the first physicists to use high-voltage accelerators to define the structure of the atom, and with Gregory Breit he used radio waves to measure the height of the ionosphere and probe its interior layers (research which underpinned the subsequent development of radar). Ernest Lawrence, inventor of the cyclotron, grew up across the street from Tuve's family in Canton, South Dakota, and the two boys were childhood friends.